1.Field of the Invention
This invention relates to ring laser gyroscopes having a plurality of sensitive axes.
2. Description of the Prior Art
Such ring laser gyroscopes have, for each axis, a gas-filled cavity or ring disposed in a plane at right angles to the associated axis, each cavity comprising three or more linear, and usually equal length limbs. Around each cavity are propagated two beams of light travelling in opposite directions, which beams are directed in continously rotating paths by mirrors located at the respective cavity corners. The beams of light are produced by laser means, the initial start-up and subsequent operation of which is by discharge between cathode and anode means associated with each cavity.
A particular form of ring laser gyroscope, to which the present invention specifically relates, comprises three four-corner cavities arranged in mutually orthogonal planes, each corner of one cavity coinciding with one corner of another cavity, so that the cavities are interconnected, and six mirrors disposed respectively at the coinciding cavity corners, the mirrors and the cavities being orientated such that the normal to each of the mirrors lies in the plane of each cavity it serves and bisects the associated corners of those cavities.
With this arrangement, a single block of material can be used to house all three cavities. It is also possible to share common cathode means with all three cavities thus reducing the number of electrodes required.
Irrespectively, since the cavities are interconnected, there are many paths along which discharge can take place and difficulties are found in reliably initiating the correct discharge paths.